We show that an equal-mass, temporary binary companion to the Sun in the solar birth cluster at a separation of ∼103AU would have increased the likelihood of forming the observed population of outer Oort cloud objects and of capturing Planet Nine. In particular, the discovery of a captured origin for Planet Nine would favor our binary model by an order of magnitude relative to a lone stellar history. Our model predicts an overabundance of dwarf planets, discoverable by LSST, with similar orbits to Planet Nine, which would result from capture by the stellar binary.
Cite
@article{arxiv.2007.10339,
title = {The Case for an Early Solar Binary Companion},
author = {Amir Siraj and Abraham Loeb},
journal= {arXiv preprint arXiv:2007.10339},
year = {2020}
}